cryptosystems

Network Security 1
Running Head: Network Security
Network Security
Advantages and Disadvantages of Asymmetric and Symmetric Cryptosystems
[The name of the writer appears here]
[The name of the institution appears here]
Network Security 2
CRYPTOSYSTEMS
A cryptosystem (or cryptographic system) is the package of all procedures, protocols,
cryptographic algorithms and instructions used for encoding and decoding messages
using cryptography. [Wikipedia.com]
As defined earlier, the system developed by implementing certain
encoding/decoding techniques, cryptographic alogthims and procedures is referred to as
the cryptosystem.
Users interact with the cryptosystem to get the encryption or decryption done
using the techniques and algorithms deployed in the system.
A cryptosystem is usually a whole collection of algorithms in which the algorithms are
labeled. These labels are referred to as “keys”. [Paolo Resmini – Standford University]
The term ‘cryptographic system’ was formed from ‘cryptography’; the science
behind information security techniques, which involves encryption and decryption.
Cryptosystems can be of two types:
 Asymmetric Cryptosystems
 Symmetric Cryptosystems
ASYMMETRIC CRYPTOSYSTEMS
In an asymmetric cryptosystem (or public key cryptosystem), there are two
different keys used for the encryption and decryption of data. The key used for
Network Security 3
encryption is kept public and so as called public key, and the decryption key is kept
secret and called private key. The keys are generated in such a way that it is impossible to
derive the private key from the public key.
The transmitter and the receiver both have two keys in an asymmetric system.
However, the private key is kept private and not sent over with the message to the
receiver, although the public key is.
SYMMETRIC CRYPTOSYSTEMS
A symmetric cryptosystem (or private key cryptosystem) uses only one key for
both encryption and decryption of the data. The key used for encryption and decryption is
called the private key and only people who are authorized for the ecryption/decryption
would know it. In a symmetric cryptosystem, the encrypted message is sent over without
any public keys attached to it.
ADVANTAGES AND DISADVANTAGES OF SYMMETRIC CRYPTOSYSTEMS
ADVANTAGES
 A symmetric cryptosystem is faster.
 In Symmetric Cryptosystems, encrypted data can be transferred on the link
even if there is a possibility that the data will be intercepted. Since there is no
key transmiited with the data, the chances of data being decrypted are null.
Network Security 4
 A symmetric cryptosystem uses password authentication to prove the
receiver’s identity.
 A system only which possesses the secret key can decrypt a message.
DISADVANTAGES
 Symmetric cryptosystems have a problem of key transportation. The secret
key is to be transmitted to the receiving system before the actual message is to
be transmitted. Every means of electronic communication is insecure as it is
impossible to guarantee that no one will be able to tap communication
channels. So the only secure way of exchanging keys would be exchanging
them personally.
 Cannot provide digital signatures that cannot be repudiated
ADVANTAGES AND DISADVANTAGES OF ASYMMETRIC
CRYPTOSYSTEM
ADVANTAGES
 In asymmetric or public key, cryptography there is no need for exchanging
keys, thus eliminating the key distribution problem.
 The primary advantage of public-key cryptography is increased security: the
private keys do not ever need to be transmitted or revealed to anyone.
 Can provide digital signatures that can be repudiated
Network Security 5
DISADVANTAGES
 A disadvantage of using public-key cryptography for encryption is speed:
there are popular secret-key encryption methods which are significantly faster
than any currently available public-key encryption method.
ROLES PLAYED BY CERTIFICATES AND THE PKI IN THE ENCRYPTION
PROCESS
Public key infrastructure (PKI) refers to a comprehensive system required to
provide public key encryption, digital certificates, and digital signatures. PKIs are
designed for key management in public-key cryptographic systems to provide the users
with digital signatures, in order to stricken the security. PKI allows participants of secure
communication to publish their public keys in authentic manner.
PKI uses the digital signatures to attest the public key of individual entities. The
Certification Authorities (CA) which play the central role in PKI, issue certificates
signing the public key of the individual entities with the digital signatures created by
encrypting the public key of the individual with its private key.
The digital certificates contain the following information: Issuing Certificate
Authority, Validity period of the certificate, the public key of the individual for which the
certificate has been created and digital signature that can be used to verify the certificate.
ANALYSIS OF THE SITUATION AT ABC COMPANY
On the basis of study conducted on the above topic, a brief analysis of the given
scenario is done and recommendations with proof are in the following text.
Network Security 6
A private link allowing east coast staff access to transactional applications and
databases residing on Midwest office servers
For this particular situation, a secret key cryptosystem is better suited. As the link
between the two office is private and no-other unidentified user is to access any of the
stations transmitting data. Both offices are to agree on a secret key to be used for the data
encryption and decryption. Being the faster of the two cryptographic methods, symmetric
cryptosystem is more appropriate for transactional applications and database access.
A planned Internet website on which customers can view their ordering and
payment information, place new orders, and communicate to customer service
representatives via e-mail
A public key cryptosystem is suitable for this situation. As the public key system
is more secure than the latter, our major concern is security of the consumer data while
the information is on Internet. Since the public key cryptographic system can be deployed
using PKI (Public Key Infrastructure) using digital signatures and separate public keys
for each user, it is more reliable and authentic method well suited for the scenario under
consideration.
Network Security 7
REFERENCES
Cryptosystems
http://en.wikipedia.org/wiki/Cryptosystem
Compare and Contrast of Symmetric Cryptosystems and Public-Key Cryptosystems
By Miguel Hidalgo
http://www.informweb.com/webportal/articles/pkicc.htm